Forbidden Love
by OVEGI
Summary: Her love for him is forbidden. She wants to love him but she is a monster. He would never love her after she has done all of that chaos. No one would love her after that. She always has to deal with so much pain. No one can love a monster.
1. Darkness

Notes: _Wassup weenies! OVEGI here! I haven't been on for a while because I was really busy but now I get a break. This is my first Adventure Time fanfic. The show just gets my interest so much so why not make a fanfic about it? So here it goes! Of course this is a Finnceline story because I think they're a cute couple. Just to give you a heads up Marceline is going to be OOC (out of character). She's going to be a dark character. Finn will slightly be OOC too. If you don't like this then don't read it. I'm warning you now. Also, if my grammar and spelling is slightly off it's because I'm using the doc manager. Something happened to my Word so I can't use it. Well...I hope you enjoy! When, you're down leave a review and let me know what you think. Enjoy!_

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**Forbidden Love**

**Chapter 1- Darkness**

Running a hand through her hair, Marceline stared at herself in the mirror. She had a hunger. A hunger to kill. She desperately needed to control herself but the urge to kill was always on her mind. It's not the blood she was looking for most of the time. It was the screams and cries of the innocent civilians that would satisfy her. She loved it. Surprisingly, she loved it more than blood. She was mad. No...she was insane.

She tried splashing water in her face to ignore the urge, but it just made her more hungry. She sighed and floated out the bathroom into her room. Just one person! Just one person! Someone who didn't matter! She needed to get rid of this urge. She stood her in dark, dull room staring at her Axe Bass. She bit her lip and looked away. _No I can't, _she thought, _I won't be able to stop if I do. _She would never be able to stop. There was no avail to it. It would end up just like before. Finn and Jake's parents. She clenched her fists just thinking back to that. She doesn't want to go back to that memory. Ever.

"Maybe I should just sleep," Marceline told herself as she floated onto her bed. "Just sleep."

She sighed closing her eyes. She would usually go out at night but not today. It would be too dangerous for the Land of Ooo. She listened to her heavy breathing making her drift off to her darkness. Her scary yet safe darkness.

_Inhale..._

_Exhale..._

_Inhale..._

_Exhale..._

_A scream..._

_Inhale..._

_Laughter..._

_Exhale..._

This time her darkness couldn't even save her. She heard every scream. Every pleasuring scream. Every delightful cry. She loved it. She couldn't hide it. She felt herself get up and out of her room and out the house. She was still trapped in her darkness. The darkness that she thought would keep her safe. She already knew her destination was the Candy Kingdom. Who would she kill this time? A random citizen? Cinnamon Bun? Peppermint Butler or perhaps Princess Bonnibel Bubblegum? Maybe even Finn...

She opened her eyes but it wasn't actually her. It was her demon. The one causing her hunger to kill. She looked at the candy people with a sadistic smile. They stared at her in horror which made he laugh. A mad laugh. She loved their reactions. It made her more happy and it's not that good happy. The real Marceline was trapped in her darkness. No one could save her. She already knew that. Hell, they even knew that. Someone rang the alarm warning the candy people that Marceline was out to attack. They started running away from her. She turned into her giant, monster bat attacking the candy people. She could feel the sweet blood splattering everywhere. She enjoyed it so much.

"Everyone in the Candy Kingdom," came a familiar voice on the loud-speaker, "please quickly run to your houses and barricade your doors and windows."

Marceline laughed as she heard that voice. "Oh Bonnibel, you're so late on this. Maybe I should pay you a visit."

She flew over to her next destination. The Candy Castle. She smashed her way through buildings and pushing candy villagers out the way. She smirked as the guards came towards her trying to attack. They couldn't kill her. They couldn't even lay a single mark on her. She smacked each and every one of the guards out of her way. She turned back to her regular, non-monster like form and entered through the window. She saw the princess standing there with a gun in her hand. It wasn't just any gun though. It was a gun she had created with her science. Marceline chuckled.

"Enough of this Marceline!" the princess snapped.

The vampire cocked her head floating closer. She smirked as Bubblegum took a step back raising the gun. "Enough of what?" she asked. "Enough of me killing innocent candy people?"

"Yes! Don't play dumb with me!"

"Chill out Bonnibel. I'm just having some fun."

"Fun killing people?!" The princess pressed her lips. This wasn't the Marceline she used to know. This wasn't the one who would tease her, call her names, and hang out with her. No, she was different. She changed so much. This was a monster. The real Marceline was trapped in her darkness. She floated a little closer to her making the princess take another step back. "I'm warning you! Don't come any closer."

"Or what? You'll shoot me with that thing?" She pointed to her gun. "Go ahead and do it Bonnie. I know you won't. You wouldn't dare shoot your best friend. You don't have the guts to."

It was true. Princess Bubblegum didn't have the guts to shoot her beloved best friend. Even if this was a monster controlling her, she still had the look of Marceline. They only stared at each other. The vampire was smirking while the princess was glaring. What happened to her? Why is Marceline like this? Why does she kill people? What the hell happened? The princess bit her lip and looked away. She saw something in those eyes. Those devilish eyes. She saw the monster. It was intimidating her. She couldn't deal with it. Marceline laughed her maniacal laugh. That laugh that the candy people or almost everyone feared. She was insane. The princess stared at her feet.

"I knew you didn't have the guts to," Marceline said as she approached her. "You're weak. Annoying. Pathetic. You make me sick."

She was still staring at her feet unable to look at the monster before her. "Look at me!" the vampire snapped which made her wince. She couldn't look at her. It hurt to look at her. She felt Marceline grab her chin and raise it.

"I told you to look at me!" she hissed. "Now you're really making me want to kill you right now."

"Marceline," the princess started, "enough of this nonsense! Look at what you're doing! This isn't like you! What happened to you?"

She shook her head. "What happened to me? Nothing has happened. You don't know anything about me Bonnie! You'll never know anything!" She removed her hand from her chin and placed it on her throat. She started choking the princess causing her to drop the gun. "Stop acting like you know me!" She liked how Bubblegum was struggling. Her screaming. Her crying. She loved it! "Where's your little hero now?" Marceline laughed while she was killing her best friend. No one could save her.

Suddenly, she heard a thump. It was a large thump but it was a small thump either. She looked over her shoulder to see Finn the human and his buddy Jake. They came through the window that she had came through. She smirked and dropped the princess. Bubblegum started coughing and gasping from the air that she had lost. Marceline turned around and stared at the two. Finn had his sword out in his hand ready for what was going to happen.

"Marceline stop this!" he snapped. "Look what you did to your friend! You almost killed her! The princess knew you before she knew me! What's wrong with you?"

The vampire placed her hands on her hips and shook her head. "Now I'm hearing the same thing from you from what I heard from Bonnie. You act like you know everything about me but you don't! No one knows anything about me."

"What about your dad?"

"Leave my father out of this! He knows nothing either. You all make me sick! I had enough of this." She lunged an attack at the boy. He dodge it and hit her sending her flying into the wall.

"Jake you go take the princess somewhere safe. I'll handle Marceline."

"Are you sure Finn?" the dog asked.

"Yes now go."

He ran over to the princess's side and took her out the room. Marceline stood and smirked.

"My Finn, you're getting stronger and stronger by the day," she told him. "But you're not stronger than me." She lunged for another attack but this time pushing the boy down. "You're weak just like everyone else." She grasped onto his neck choking him like she did to Princess Bubblegum. He struggled but her grip was tight. He took the sword and stabbed her on her side. She hissed letting go of him and falling back. Finn gently placed his hand on his throat slowly breathing for air as her got up. He stared at the vampire who was holding her wound. He wasn't surprised when he saw it heal.

"You missed," she pointed out looking up at him.

"I know," he replied. "I don't want to kill you Marceline."

She got up. "I know you don't. Just like Bonnie, you wouldn't have the guts to kill me."

"Marceline..." He sighed.

She started to do that devilish laugh again. He didn't know what to say. She knew that he couldn't do it even if he wanted to.

"You call yourself a hero but you can't stop me." She smirked. "You can't do anything."

He clenched onto his sword and gritted his teeth. He pushed against his muscles. He was shaking but not in fear. No, not in fear but in anger. This time he ran to attack her. She smack him making him take a step back, grabbed his wrist, and snatched the sword out of his hand. She floated higher still holding onto the sword and the boy. She again, grasped his neck. The vampire raised him to her face. A smirk crept on her face.

"You may not be able to kill me," she started placing the sword against his chest, "but I am able to kill you."

Finn struggled to break out of her hold. Her red eyes pierced into his blue eyes then he saw it. This wasn't Marceline. The real Marceline was trapped. Trapped in the darkness beneath this monster. He could see it. No one could save her.

"I really did like you Finn," she whispered in his ear. "It's ashamed that I'm going to have to kill you."

He clenched his eyes shut ready to feel the pain. He should have had Jake stay with him so he could help him stop Marceline. It was too late now. He wanted to scream but for some reason he didn't. Either he couldn't or he wouldn't. He felt the a terrible stab of pain in his stomach. He could have sworn she placed the sword at his chest. He felt tears stream down his eyes. He still didn't scream. That pissed the vampire off.

"Why aren't you screaming?!" she snapped letting go of his neck and grabbing onto his collar instead. "Don't you feel pain?!" She started shaking him. "Don't you?!"

She took the sword out of him making him gasp then she dropped him. He hit the floor hard. He coughed up blood. The vampire floated towards him with a glare this time. She turned around hearing voices coming from outside the room.

"Finn! Finn!" It was the dog.

She turned back to the boy. "I'll leave you here to bleed to death. Maybe your friends will be able to save you maybe not." She smirked. "Bye, bye my little hero." Then she float out the window leaving him in the middle of the floor. He watched her leave. His felt light headed and passed out.

* * *

"Finn!" called a familiar voice.

He slowly opened his eyes. "J-Jake?" he answer. "What happened?"

Jake sighed. He remember taking the princess out the castle then getting help. Next thing he knew, Finn was on the ground passed out with a pool of blood. He didn't know Marceline would actually do that then again, he always suspected that she was suspicious. He was always afraid of her but tried to get used to her.

"You were stabbed in the stomach and then you passed out," he told the boy.

Finn blinked. "Oh that's right." He looked around and saw that he was in the hospital. He was also shirtless. He looked under the covers and saw rapping paper around his lover abdomen.

"What happened to Marceline?" he asked the dog.

"I don't know. She was gone when we saw you."

Finn looked at his hands. "Is Peebles okay?"

"Yea she's fine. She went to go get some rest." Jake stared at him. "What happened to Marceline? Why is she this way?"

He bit his lip. "I don't know man but what ever happened to her, all I know is that she's trapped in darkness."

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**Notes: **_Well, well, well, that's the end of chapter one. Please review and let me know what you think. I hope you know I kept putting the word darkness in this chapter on purpose. If you have any questions they'll probably be answered throughout the story. Anyway til next time my pretties._


	2. Let's Go Hunting

**Notes: **_Yo! I'm baaaaaack and with another chapter my pretties. So far I love the reviews and keep them coming. I'd love to know what you think about the story so far. It just makes me wanna continue. ^_^ So this chapter is mostly going to just have Finn but it will switch to Marceline from some time. Don't you worry my little Mar-Mar fans. Finnceline will be in later chapters but for now we just wait. So without further a do, next chapter!_

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**Forbidden Love **

**Chapter 2- Let's Go Hunting**

Jake stayed in the hospital with his buddy all morning but eventually he had to leave. He needed to go speak with Lady about something. Finn couldn't sleep. He was still thinking about what happened. He was thinking about Marceline. He held his stomach to where she had stabbed him and turned his head towards the window.

"Marceline..." he said then sighed. "I don't know what's going on but...I'm going to save you. I'll save you from your darkness."

He heard a knock on the door. "Come in!" Princess Bubblegum entered the room. She pulled up the chair that Jake sat in before and took a seat. She stared at Finn.

"Hey PB," he greeted.

"Hey Finn," she replied. "How are you feeling?"

"A bit better." He looked down at his stomach. "The wound still hurts a little but I'm fine."

She smiled. "Well that's good."

"Any word in sight of Marceline." He was still worried if she caused more damage while he was knocked out.

"No, I had candy guards check her house but she wasn't there." She ran her hand over her hair. "I have no idea where she went off to."

Finn sighed. Where could she be? She can't be at another kingdom can she? She probably corrupted more chaos while he was knocked out. Where ever she was he needed to know and fast. It was silent for a while. The princess studied the boy to see in his emotions how he was really feeling. She saw the look of concern on his face. He looked at up her.

"What?" he asked as he felt his face. "Is there something on my face?"

She giggled. "No no Finn. There's nothing on your face."

"Oh, then what is it?"

"It's just you. You look concerned."

He looked at his hands then back up at the princess. He was definitely concerned. He was concerned about Marceline. He wanted to know how and what she was doing. He hoped that she wasn't attacking any other kingdoms but it was sunny out. Vampires hate the sun. True fact. Some of the worry faded away because of that but she could be in pain. Even though she almost killed her and Princess Bubblegum and killed some of the candy people, he wanted to help her. The real Marceline wouldn't do that.

"I am concerned," Finn finally answered. "I'm worried about her PB. What if she is hurting inside?"

The princess gave a puzzled look. She too was worried about the young vampire but she didn't know what Finn meant by hurting inside. "What are you talking about Finn?"

"I saw it in her eyes," he told her. "Not only did I see the demon but I saw Marceline too. She looked scared and helpless. I want to save her."

Bubblegum sighed. All she saw in Marceline's eyes was a monster. How could Finn see the real Marceline? Can he see things that she can't?

"How are you planning to save her?"

He was startled by that question. He didn't actually know how to. He only wanted to help. He wanted to save her from her darkness. "I...I don't know. I just want the regular, teasing, funny Marceline back."

"I do too Finn but-"

"I want to go find her," he interrupted. "As soon as possible."

"Finn..." She didn't know how much Finn cared for the vampire. Sure they liked the same things and hung out all the time but she thought that the boy had feelings for her. She shook her head out of that thought. Now is not the time to become jealous. Was she though?

She was shocked when she saw him get up and out of the bed. He grabbed his shirt off the dresser and threw it on. He looked back at the princess.

"Finn you can't go out there. You need to stay in the hospital. You're not fully healed yet."

"I don't care. I'm not going to let another kingdom get ruined. I have to do something. I can't just sit here and call myself a hero. I don't want to fail again." He referred the failing again when he let Marceline get away. "Now, where's my bag, hat, and sword?"

She stood up and touched the boy's face. "Finn, are you sure about this?"

"Yes I'm sure. I'm a hero." He gave her a reassuring smile. "Don't worry about me. So where's my things at?"

The princess pointed to the closet. "In there."

Finn walked to the closet and took his things. He looked at the sword as saw his blood from earlier. He glanced back at Bubblegum, nodded, and walked out.

"Be careful Finn!" she called to him.

"I know!" he called back.

_I need to tell Jake, _he thought as he headed through the hospital.

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The vampire cursed under her breath. What happened to her? She nearly killed Finn. Then she thought that he could have bled out and died? No, he couldn't. He's strong. He couldn't die from a stomach wound. Can he? She sighed. Marceline had stayed deep in the cave for the rest of the night. It was her second house for when anything had happened. She was sitting on the ground staring at the wall. She laughed.

"I truly am mad," she said chuckling. "I'm laughing at a wall. What's wrong with me?"

She licked some of the left over blood from last night. It hadn't dried up. It was still wet. It was still good too. She loved the sweet taste of blood in the morning. It kept her going but also the way blood was flowing out of Finn was just unbearable. Why didn't she drink some of it? It didn't even get on her. She never had human blood before.

She got up and walked further into the cave. She was looking for something. She needed to get out of this cave for a while. She left her Axe Bass at her other home. This made her bored. She really wanted to play some music.

"I'll just go back for it," she told herself. "Now where is that sunbrella at? There you are!"

She saw it leaning against a large rock. She opened it and held it over her head. Usually vampires hate the sun but she actually likes it. It soothes her so she takes her large hat or sunbrella out with her so she can enjoy the outdoors. She floats out of the cave and outside. She goes to the direction to where her other house is. Marceline hopes no one will see her. She just wants to get as far away from the Candy Kingdom as possible.

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Finn went back to the treehouse calling out Jake's name. He found him taking a nap on the couch while BMO was whistling a little tune. The game turned around and smile happy to see him.

"Hey Finn!" he shouted. "You're back already. I'm glad you're okay."

"Sup BMO," he replied. "Wake Jake for me?"

The game did so nudging the dog. He kept calling his name. Jake is a deep sleeper but her finally woke up. He was startled to see Finn. He then yawned and sat up scratching his head.

"Hey Finn, why are you out of the hospital?" he asked.

"We need to find Marceline," he answered.

Jake cocked and eyebrow. "Wait why she-"

"We need to go now." The boy looked serious. Jake has seen this face many times but not like this. He was really serious. The dog sighed. If Finn is this serious about her then he will go too. He waited for Jake to answer.

"What time is it?" Jake asked while a stupid grin.

"Adventure time?" Finn replied in a questioned tone.

"Nope...huntin time!"

"Yea!"

The two bumped fist. Finn looked at BMO. "Keep the house safe while we're gone BMO."

"Okay Finn," the came answered. "You two be careful."

The boy and his dog left the treehouse and headed to where ever. They didn't know where they were going but they had to find her. Somewhere. Anywhere.

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**Notes: **_Hello again! That's it for chapter two. Don't forget to review. Let me know what you think so far. Any ideas what might happen when they find Marceline? Let me know. Any way! Sayonara! Chapter 3 will come ASAP my little Mar-Mar fans._


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